Balding deer being ravaged by exotic lice

Researchers combing the hair of a captured fawn find an infestation of exotic lice, which they believe are causing baldness and deer deaths across the state.

Researchers combing the hair of a captured fawn find an infestation of exotic lice, which they believe are causing baldness and deer deaths across the state.

Photo: Greg Gerstenberg, CDFW

Photo: Greg Gerstenberg, CDFW

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Researchers combing the hair of a captured fawn find an infestation of exotic lice, which they believe are causing baldness and deer deaths across the state.

Researchers combing the hair of a captured fawn find an infestation of exotic lice, which they believe are causing baldness and deer deaths across the state.

Photo: Greg Gerstenberg, CDFW

Balding deer being ravaged by exotic lice

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A mysterious, and apparently deadly, scourge that is causing deer across California to go bald has been linked to an invasion of aggressive exotic lice that are savaging local fauna, wildlife officials say.

The bad hair, which researchers are calling hair-loss syndrome, is becoming epidemic across the state and is believed to be a factor in numerous deer deaths, according to the California Department of Fish and Wildlife.

"It could be a major problem," said Greg Gerstenberg, the department's senior wildlife biologist, who is leading a statewide research project to find out what is behind the bug and baldness blitzkrieg. "That's why we are concerned and spending the time and effort to look into it in a more detailed manner."

Gerstenberg said he first became aware of the issue in the spring of 2009 when an almost completely hairless deer was found dead near Groveland in Tuolumne County, on the western slope of the Sierra Nevada. Wildlife officials subsequently found 240 dead balding deer over a five-month period in the mountains outside Yosemite National Park.

To date, researchers have captured and collected hair and blood samples from more than 600 deer and elk across California with symptoms ranging from a scruffy-looking coat to almost complete baldness. Hair-loss syndrome has been identified in San Mateo County and at least 14 other counties around the Sierra foothills, in the Sacramento Valley and along the north coast, according to a state ungulate hair-loss study map.

Gerstenberg said the resident deer population in Tuolumne County has been hit the hardest, but migrant and resident deer on the coast range and near the San Luis Reservoir in Merced County, have also recently suffered heavy hair loss. The problem also recently spread to Tulare, Placer and San Diego counties.

Lice from Europe and Asia

The shedding deer all seem to have one thing in common, an abundance of exotic lice. The lice plucked from the dead deer in the Tuolumne area were identified by the National Veterinary Service Laboratories, in Ames, Iowa, as Bovicola tibialis, a species that normally feeds on fallow deer native to Europe and Asia.

It's a lousy situation for the besieged deer, Gerstenberg said. The bloodthirsty insects multiply in the winter and reach their peak population in the spring, right about now. Deer normally have fewer than two dozen native lice on them, but Gerstenberg has been finding thousands of lice on the deer in Tuolumne.

"In places on the body you almost can't see the skin, there are so many," he said. "That's part of why we are concerned. These are biting lice. There are behavioral changes with an infection like that. The deer are biting and scratching, which is why we think it might be resulting in the hair loss."

The marauding lice do not feed on humans, but they are clearly impacting migratory populations of California deer, which have an unusually low fawn survival rate, according to state regulators. The spike in deer mortality also appears to be associated with poor nutrition, internal parasites spread by lice, and increased predation by cougars and coyotes taking advantage of the poor health and lack of attentiveness of the hoofed creatures due to their feverish itching, researchers said.

Mineral deficiencies found

Mineral deficiencies were detected in most of the dead deer from Tuolumne County, prompting biologists to begin collecting forage material for testing to determine whether ecological changes, like an influx of invasive plants, may be having an effect on their diet and consequently their fur.

"It has been speculated that this condition may be attributed to an environmental deficiency of copper or selenium or some other underlying environmental factor such as a difficult-to-detect disease agent," said Pam Swift, the state veterinarian.

Hair loss not new

Hair-loss syndrome isn't exactly new. It has been documented in Columbian black-tailed deer in western Oregon and Washington since 1996. Those cases were connected to another exotic louse called Damalinia (Cervicola).

That louse species, believed to come from Sitka black-tailed deer, a subspecies of mule deer native to Alaska, spread over the past few years into Humboldt and Mendocino counties, according to several studies. Hair loss associated with Damalinia was recently documented in California mule deer and black-tailed deer as far south as San Mateo County, fish and wildlife officials said.

The Bovicola lice must have come from fallow deer, Gerstenberg said, but how they ended up on mule deer in the Sierra is a mystery. Nonnative deer from Europe and Asia have been introduced in places over the years often for hunting purposes, including in woodland areas of western Marin County, but there are no records of fallow deer in the Groveland area. The nonnative deer in Marin were mostly killed off during an eradication campaign a few years ago.

"We don't know how they became established," he said. "It could have been from a variety of sources."

The researchers are counting and identifying lice on each deer they capture, applying radio collars to track the deer and, in some cases, treating the animals. The idea is to determine just how widespread invasive lice species are in California, document their spread and determine exactly what role they play in causing California's deer to go bald.